Apparatus and method for providing high speed download service of multimedia contents

ABSTRACT

An apparatus for downloading a multimedia file including a file converter configured to convert a larger multimedia file into a smaller multimedia file by deleting prescribed medial information based on a media format contained in the larger file. Further, the file converter converts the larger file into the smaller file by deleting multi bit-rate media not corresponding to a selected bit rate or by deleting enhancement layer video.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to Korean Application No. 64501/2003, filedon Sep. 17, 2003, the entire contents of which are hereby incorporatedin its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a VOD (Video on Demand) service, andmore particularly to an apparatus and method for providing a high speeddownload service of multimedia contents capable of converting a formatof a multimedia contents file used for a download service.

2. Background of the Related Art

A multimedia contents file for a VOD service may be created in an MP4file format, for example, and constructed to effectively implement astreaming service. For example, FIG. 1 illustrates a structure of ageneral MP4 file format. As shown, the MP4 file is roughly divided intoa ‘moov’ part corresponding to a header part and a ‘mdat’ partcontaining actual media information.

The ‘moov’ part includes a plurality of ‘trak( )’ boxes holding metainformation on each media according to a type of the media included inthe multimedia contents file. That is, the trak boxes include a‘trak(video)’ including meta information on video information, a‘trak(audio)’ including meta information on audio information, and a‘trak(hint)’ provided for a real time streaming service.

The multimedia contents file constructed with such a file format asshown in FIG. 1 is suitable for a streaming service. The VOD serviceprovides the streaming service and a download service together based onthe above-structured multimedia contents file.

In general, when creating a file suitable for the streaming service,functions making an internal structure of the file complicated areincluded to handle problems that may arise when the stream service isprovided on a real time basis. A typical function is the construction ofa multiple video trak by applying a temporal scalability. In moredetail, FIG. 2 illustrates an example of a streaming service using atemporal scalability-based file format, in which the transmission of abase layer video and an enhancement layer video are controlled accordingto an available bandwidth of a network.

In other words, if an available bandwidth of the network is low, an RTP(Real Time Protocol) streaming server carries only the base layer videoon an RTP packet, whereas if the available bandwidth of the network ishigher than a prescribed value, the RTP streaming server transmits theenhancement layer video having a B (bi-directional)-frame as well as thebase layer video so that a user can be provided with a video servicewith a high frame rate. In this instance, however, although the B-frameis advantageous in the aspect of the transmission error and scalability,it increases a transmission quantity.

Further, if the available bandwidth of the network is too low totransmit the base layer video, the RTP streaming server transmits onlyan I (intrinsic)-frame for service. However, in such a streaming servicemethod, significant data is added to additionally store the enhancementlayer video or the like, so that when the multimedia contents file isprovided as a download service, the amount of data to be transmitted issignificantly increased.

Further, because the number of packets required for transmission of theentire multimedia contents file is increased, the user's service fee isincreased and a lot of time is required for the user to download thefile for service.

Turning now to FIG. 3, which illustrates a format of the multimediacontents file including a multi bit-rate media. One multimedia contentsfile includes multi bit-rate coded video and audio data. The multimediacontents file as shown in FIG. 3 has a structure that can be serviced byselecting video and audio data suitable for the available bandwidth ofthe network such as the temporal scalability.

If the available bandwidth of the network is not less than 256 Kbps, avideo V3 and an audio A3 are streaming-serviced, while if the availablebandwidth is not more than 64 Kbps, quite low, a video V1 and an audioA1 are streaming-serviced.

However, even though the multimedia contents file having the structureincluding the multi bit-rate coded media is used for the downloadservice, the number of packets required for transmission of the entirefile is increased, which results in a higher service fee and increases auser's standby time for using the service.

SUMMARY OF THE INVENTION

Accordingly, one object of the invention is to address at least theabove problems and/or disadvantages and to provide at least theadvantages described hereinafter.

Another object of the present invention is to provide a download servicethat converts a file format suitable for a real time streaming serviceinto a file format suitable for a download service.

To achieve at least the above objects in whole or in parts, the presentinvention provides a novel apparatus for downloading a multimedia fileincluding a file converter configured to convert a larger multimediafile into a smaller multimedia file by deleting prescribed mediainformation based on a media format contained in the larger file.Further, the file converter converts the larger file into the smallerfile by deleting multi bit-rate media not corresponding to a selectedbit rate or by deleting enhancement layer video.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objects and advantages of the invention may be realizedand attained as particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 is an overview illustrating a general MP4 file format;

FIG. 2 is an overview illustrating a streaming service using a temporalscalability-based file format;

FIG. 3 is an overview illustrating a format of a multimedia contentsfile containing a multi bit-rate media;

FIG. 4 is a block diagram illustrating a construction of an apparatusfor providing a high speed download service of multimedia contentsaccording to the present invention;

FIG. 5 is an overview illustrating the conversion of a large capacitymultimedia contents file containing an enhancement layer video into asmaller capacity multimedia contents file;

FIG. 6 is another overview illustrating the conversion of a largecapacity multimedia contents file containing multi bit-rate media into asmaller capacity multimedia contents file; and

FIG. 7 is a flow chart illustrating a high speed download service ofmultimedia contents according to the present invention.

BEST MODE OF THE INVENTION

An apparatus and method for providing a high speed download service ofmultimedia contents according to the present invention will now bedescribed with reference to the accompanying drawings.

In more detail, FIG. 4 is a block diagram illustrating a construction ofan apparatus for providing a high speed download service of multimediacontents according to the present invention. As shown in FIG. 4, theapparatus includes a file converter 100 for selectively deleting mediainformation according to an internal attribute of a multimedia contentsfile for a streaming service, and for converting it into a multimediacontents file for a download service; and a file transmitting unit 200for transmitting the multimedia contents file for the download serviceoutputted from the file converter 100 to a terminal using Hyper TextTransfer Protocol (HTTP), for example.

The file converter 100 deletes certain types of media information toconvert a large capacity multimedia contents file into a smaller filesuitable for downloading. In this instance, the multimedia contents filefor the download service maintains a same basic format of the multimediacontents file for streaming.

The apparatus for providing a high speed download service of multimediacontents for streaming operates as follows.

First, when a download service of an arbitrary large capacity multimediacontents is requested by a terminal, the file converter 100 determinesan internal attribute of the corresponding multimedia contents. That is,the file converter 100 determines whether or not the multimedia contentscontains an enhancement layer video or a multi bit-rate media.

If the multimedia contents contains enhancement layer video, the fileconverter deletes media information related to the enhancement layervideo, while if the multimedia contents contains multi bit-rate media,the file converter deletes media information except for a bit rateselected by a user. Through this process, the file converter 100converts a large file into a smaller file. The transmitting unit 200then transmits the smaller file to a corresponding terminal.

Turning next to FIG. 5, which illustrates conversion of a large capacitymultimedia contents file containing an enhancement layer video into asmaller file. As shown, the large capacity multimedia contents fileincludes a ‘moov’ part (a header part), and a ‘mdat’ part (a media datapart). The ‘mdat’ part includes base layer and enhancement layer video.

When the large capacity multimedia contents file is inputted, the tracksof the ‘moov’ part and the media data of ‘mdat’ part related to theenhancement layer video are deleted to convert the large file into asmaller capacity multimedia file. In this instance, because the baselayer video and the enhancement layer video are mutually independentcontent, the deletion can be performed without affecting the base layervideo. Further, in the multimedia contents file, a spatial positionvalue (chunk_offset) of the remaining non-deleted media data isadjusted, and if there is a hint track in the ‘moov’ part, the hinttrack is also deleted.

Next, FIG. 6 illustrates conversion of a large capacity multimediacontents file containing multi bit-rate media into a smaller filesupporting only a single bit rate of 64 Kbps, for example. As shown,when the large file is inputted, the track of the ‘moov’ part and themedia data of ‘mdat’ part except for a bit rate selected by a user(e.g., 64 Kbps) are deleted to convert the large file into a smallerfile.

In addition, a hint track of the ‘moov’ part is deleted because itincludes information that is not required for the download service.Further the tracks V2, V3, A2 and A3 as well as the meta information ofthe media data are deleted from the ‘moov’ part because they includeinformation independent from the tracks V1 and A1 for the 64 Kbps bitrate. Further, data in media data part other than ‘V1’ and ‘A1’ relatedto 64 Kbps are also deleted.

In addition, an alternate_group field value among fields of the trackheader box and header information of the tracks V1 and A1 is alsoconverted. The alternate_group field is a value existing in every track,and is used to determine the media data contents.

For example, if the alternate_group values of two or more tracks are thesame natural number, the two or more tracks are determined to be videotracks, which have the same content even though the tracks havedifferent bit rates. If the alternate_group value is ‘0’, each videotrack is determined to be a video track with a different content.

As shown in FIG. 6, because the multimedia contents file containingmulti bit rates includes the same content of media data having threedifferent types of bit rates of 64 Kbps, 128 Kbps and 256 Kbps, thealternate_group value is the natural number of the same value, not ‘0’.

However, when a large capacity multimedia file is converted into a smallcapacity multimedia contents having a single bit rate, because eachmedia data has a different content, the alternate_group value should be‘0’. Thus, the alternate_group value recorded in the header of the ‘trak(V1)’ and the alternate_group value recorded in the header of ‘trak(A1)’ are converted to ‘0’. Further, in the large capacity multimediacontents file, the chunk_offset value indicating the spatial position ofthe remaining media data which has not been deleted is adjusted.

As shown in FIGS. 5 and 6, the file converter 100 reduces the size ofthe file by converting the structure of the large capacity multimediacontents file suitable for the streaming service, thereby shortening thetime required for downloading the file.

Turning now to FIG. 7, which is a flow chart illustrating a method forproviding a high speed download service of multimedia contents accordingto the present invention. As shown, when the user requests a downloadservice of an arbitrary multimedia contents file (step S11), the fileconverter 100 determines whether there is a multi bit-rate media in thefile (step S12). Note, the original multimedia file is a large filehaving a complicated internal structure suitable for the streaming.

If there is multi bit-rate media in the file (yes in step S12), thetracks of ‘moov’ part and the media data of ‘mdat’ part, which have norelation to the bit rate selected by the user are deleted (step S13).Further, the alternate_group value of the track header box of the ‘moov’part is set to ‘0’ (step S14). That is, if there is a multi bit-ratemedia in the file, the alternate_group value of the track header box isthe same natural number, not ‘0’, but when the file is reduced to a fileof a single bit rate, the alternate_group value is set to ‘0’ so thateach media data signifies a different content.

If there is no multi bit-rate media in the file (no in step S12), adetermination is made as to whether or not there is enhancement layervideo in the multimedia file (step S15). If there is enhancement layervideo (yes in step S15), the tracks of the ‘moov’ part and the mediadata of the ‘mdat’ part related to the enhancement layer video aredeleted (step S16). Note, the multimedia contents file includes the baselayer video and the enhancement layer video, each having a differentcontent.

After the file is reduced to the single bit rate or after the mediainformation related to the enhancement layer video is deleted, achunk_offset value indicating a spatial position of the remainingnon-deleted media data is adjusted (step S17). Next, any hint tracksrelated to the streaming service are deleted (step S18), therebycreating a small capacity contents file suitable for downloading (stepS19). The small capacity multimedia contents file is then transmitted tothe terminal which has requested for the downloading service (step S20).

Further, if there is no multi bit-rate media and the enhancement layervideo in the original larger file (no is steps S12 and S13), theoriginal file is not reduced (step S21) and transmitted as the originalfile (step S20).

As so far described, the apparatus and method for providing a high speeddownload service of multimedia contents of the present invention havethe following advantages.

Because the large capacity multimedia file for streaming is convertedinto a smaller file, the time required for downloading the file isreduced, and the standby time for using the service is reduced. Further,because the file is reduced in size, the user's cost of the VOD isreduced.

This invention may be conveniently implemented using a conventionalgeneral purpose digital computer or microprocessor programmed accordingto the teachings of the present specification, as well be apparent tothose skilled in the computer art. Appropriate software coding canreadily be prepared by skilled programmers based on the teachings of thepresent disclosure, as will be apparent to those skilled in the softwareart.

The invention may also be implemented by the preparation of applicationspecific integrated circuits or by interconnecting an appropriatenetwork of conventional component circuits, as will be readily apparentto those skilled in the art. The present invention includes a computerprogram product which is a storage medium including instructions whichcan be used to program a computer to perform a process of the invention.The storage medium can include, but is not limited to, any type of diskincluding floppy disks, optical discs, CD-ROMs, and magneto-opticaldisks, ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, or anytype of media suitable for storing electronic instructions.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the present invention. The presentteaching can be readily applied to other types of apparatuses. Thedescription of the present invention is intended to be illustrative, andnot to limit the scope of the claims. Many alternatives, modifications,and variations will be apparent to those skilled in the art.

1. An apparatus for downloading a multimedia file, comprising: a fileconverter configured to convert a larger multimedia file into a smallermultimedia file by deleting prescribed media information based on amedia format contained in the larger file.
 2. The apparatus of claim 1,wherein the file converter converts the larger file into the smallerfile by deleting multi bit-rate media not corresponding to a selectedbit rate or by deleting enhancement layer video.
 3. The apparatus ofclaim 1, wherein a format of the media comprises: a format containingmulti bit-rate media; and a format containing enhancement layer video.4. The apparatus of claim 1, wherein if there is multi bit-rate media inthe larger file, the file converter deletes tracks of a ‘moov’ part andmedia data of a ‘mdat’ part except for a selected bit rate and adjusts avalue of a track header box in the ‘moov’ part.
 5. The apparatus ofclaim 4, wherein adjustment of the track header box value is performedso an alternate_group value indicating alikeness of media data contentis set to ‘0’, a chunk_offset value indicating a spatial-position ofnon-deleted media data is adjusted, and a hint track is deleted.
 6. Theapparatus of claim 1, wherein if there is an enhancement layer video inthe larger file, the file converter deletes tracks of a ‘moov’ part andmedia data of a ‘mdat’ part related to the enhancement layer video andadjusts a value of the track header box of ‘moov’ part.
 7. The apparatusof claim 6, wherein adjustment of the track header box value isperformed so a chunk_offset value indicating a spatial position ofnon-deleted media data is adjusted, and a hint track is deleted.
 8. Amethod for downloading a multimedia file, comprising: converting alarger multimedia file into a smaller multimedia file by deletingprescribed media information based on a media format contained in thelarger multimedia file.
 9. The method of claim 8, wherein converting thelarger file into the smaller file is performed by deleting multibit-rate media not corresponding to a selected bit rate or by deletingenhancement layer video.
 10. The method of claim 8, further comprising:receiving a download service request for the larger multimedia file; andtransmitting the smaller file to a terminal after converting the largerfile into the smaller file.
 11. The method of claim 7, whereinconverting the larger file into a smaller file comprises: checking amedia format in the larger multimedia file; deleting the prescribedmedia information; and adjusting a track header box value for thedeleted media information.
 12. The method of claim 11, wherein checkingthe media format comprises: determining whether a multi bit-rate mediais contained therein; and determining whether an enhancement layer videois contained therein.
 13. The method of claim 8, wherein converting thelarger file into the smaller file, comprises: deleting tracks of ‘moov’part and media data of an ‘mdat’ part except for a bit rate selected bya user; and deleting tracks of a ‘moov’ part and media data of an ‘mdat’part related to enhancement layer video.
 14. The method of claim 11,wherein adjusting the track header box value comprises: adjusting achunk_offset value indicating a spatial position of non-deleted mediadata.
 15. The method of claim 11, wherein adjusting the track header boxvalue comprises: setting an alternate_group value indicating alikenessof the media data to ‘0’.
 16. The method of claim 8, wherein convertingthe larger file into the smaller file comprises: deleting a hint trackindicating a streaming service.